Process of hardening artificial stone or the like.



UNITED STATES PATENT QFFIGE.

CARL RENSING, OF BERLIN, GERMANY.

PROCESS OF HARDENING ARTIFICIAL STONE OR THE LIKE.

SPECIFICATION forming part of Letters Patent No. 681,580, dated August27, 1901.

Application filed November 1, 1900. Serial No. 85,179- (No specimens.)

To all whom it may concern.-

Be it known that I, CARL RENSING, a subject of the Emperor of Germany,residing at Lichtenberg, near Berlin, in the German Empire, haveinvented new and useful Improvements in Processes of HardeningArtificial Stone or the Like, of which the following is a specification.

For hardening calcareous sandstones it has heretofore been usual tointroduce the bricks into a boiler, so-called hardening-boiler, and tosubject them for some time to a certain steam-pressure. The generationof the steam was effected in a separate boiler. A

' similar process is gone through in other chemical technical operationsin which certain chemical transformations are effected by pressure andheat. Steam-pressure and heat are absolutely necessary for effecting atechnical result such as hardening or chemical decomposition. Thegeneration of pressure by steam alone is, however,- too costly,- as verylarge quantities of steam must be supplied for filling thehardening-boiler. The steam-generator is also from time to time strainedor overworked and this gives rise to great consumption of fuel andconsiderable loss. Furthermore,the steam is very moist,because' it issuddenly removed from the generator, so that considerable condensationtakes place,particularly as the temperature and the pressure in thehardening vessel are naturally Very low at the commencement of theoperation. The steam is spent in heating the lining of the vessel,sothat its pressure gradually decreases until the desired temperature inthe hardening vessel is attained.

Now it is the object of this invention to obviate these disadvantagesand to have the hardening vessel under the requisite pressure as soon aspossible after the commencement of the operation. To this end I forceinto the operating vessel cold or heated air or any other suitableneutral gas-such, for

example, as nitrogen, oxygen, or hydrogenuntil the said vessel isbrought under a high pressure, which is approximately that under whichthe operation is to be effected. The steam is then allowed to fiow intothe hardening vessel, which is filled with the pressure air or gas. Ifthe operation is to be effected, for example, under a pressure of aboutseven atmospheres, the air, which may be heated or merely purified, isforced into the operat- 5 5 ing vessel until a pressure of, say, sixatmospheres is attained, after which steam at seven atmospheres isallowed to flow in. There is then a pressure in the hardening vessel ofabout seven atmospheres, which is what is diminished by watercondensation, as would be the case with a vessel filled with steamalone. In addition to this the steam which is in suspension in themediumthat is to say, the air, for example sufiers less condensation, asair isa worse conductor of heat than water-vapor;

It will be obvious that the invention will not be altered if steam befilled into the ves-' sel before the air, this being advantageous on theground of economy where waste steam is obtainable.

Having now particularly described and as certained the nature of my saidinvention and in what manner the same is to be performed, I declare thatwhat I claim isl. The herein-described process of hardening artificialstone, which consists in sub jecting the articles to be treated, whileinclosed, to the action of air and steam combined under high pressure,whereby economy of steam is effected and undue condensation of the steamis prevented, substantially as described.

2. The herein-described process of hardening artificial stone and thelike which con- 95 sists in subjecting the articles to be treated, whileinclosed, to the action of a neutral gas at high pressure and thenadmitting steam at still higher pressure, to commingle with said neutralgas.

3. The herein-described process of hardening artificial stone and thelike, which consists in subjecting the articles to be treated to theaction of compressed air at substantially six atmospheres and admittingsteam 105 at a pressure greater than six atmospheres.

CARL RENSING. Witnesses:

ROBERT BORNCMANN, THEODOR ScnMUTz.

